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From the article: > TS It's certainly the case that a lot of CRDTs are really complicated, especially in those instances where they represent some sort of comp
by tracnar 6y ago
From the article:
> TS It's certainly the case that a lot of CRDTs are really complicated, especially in those instances where they represent some sort of complex interrelated state. A classic example would be the CRDTs used for document editing, string interjection, and that sort of thing. But the vast majority of machine-generated data is of the write-once, delete-never, update-never, append-only variety. That's the type of data yielded by the idempotent transactions that occur when a device measures what something looked like at one particular point in time. It's this element of idempotency in machine-generated data that really lends itself to the use of simplistic CRDTs.
So for this particular use case, the CRDT is simple and they want to favor availability over consistency. I'm not sure if they provide further guarantees, e.g. from the description in the article it seems that temporary holes in the time series would be allowed if updates would arrive out-of-order.
The article also mentions Cassandra, it seems they went for a different design so progress is more quickly visible in the DB (among other reasons I suppose).
> What we wanted was a topology that looked similar to consistent hashing databases like DynamoDB or Riak or Cassandra, but we also wanted to make some minor adjustments, and we wanted all of the data types to be CRDTs [conflict-free replicated data types]. We ended up building a CRDT-exclusive database. That radically changes what is possible, specifically around how you make progress writing to the database.